Exhaust muffler

ABSTRACT

Disclosed herein is a muffler comprising an elongated housing including a generally cylindrical side wall and, at each end thereof, an inwardly concavely dished end wall, and a dished partition dividing the housing into an inlet chamber and an outlet chamber and extending convexly with respect to the inlet chamber, together with a beveled port which is located in the partition, which extends from the inlet chamber into the outlet chamber and which includes a tubular part having a length extending parallel to the length of the housing and being formed, at least in part, by the material of the partition with an inlet having a margin which merges with the partition and which has an arcuate form in a plane extending radially of the length of the tubular part, and an outlet tube including an inlet portion extending lengthwise within the housing through the partition and having an inlet in the outlet chamber and including an outlet portion extending at least partially in the inlet chamber and outwardly through said side wall.

' United States Patent 191 I {S1111 3,776,366-

Betts et al. v i 1451 Dec. 4, 1973 EXHAUST MUFFLER [75'] Inventors: E. Douglas Betts, Gurnee Ill.; im f' h wilkmson I Donald Hanson, Greendale, Assistant Exammer John F. Gonzales Donald Stephenson, Sussex, both Attorney-Robert E. Clemency et al.

[73] Assigneez Outboard Marine Corporation, [57] ABSTRACT -Waukegan, lll'.

' Disclosed herein is a muffler comprising an elongated [22] Filed: July 24,1972 housing'including a generally cylindrical side walland,

. at each end thereof, an inwardlyconcavely dished end [211 App!' 4 wall, and a dished partition dividing the housing. into an inlet chamber and an outlet chamber and extending -S- 8 1 l'8l/60 convexly with respect to theinlet chamber, together [51] Int. Cl.....; .F01n' 1/08' with a beveled port which is located in the partition,

[58] Field Of Search 181/40, 53, 54, 56, which extends from the inlet chamber into the outlet /5 53 chamber and which includes a tubular part having a v Y length extending-parallel to the length of the housing [56] References Cited Q and being formed, at least in part, by the material of UNITED STATES PATENTS the partition with an inlet having a margin which 2,825,421 3 1958 Bryant .l 181 53 X merges with h Partitim and which has 1,998,385 4 1935 Powell 181/57 foml in a Plane extending radially 0f the length of the 2,239,549 4/1941 chi l 131 57 tubular part, and an outlet tube including an'inlet por- 2,520,756 8/1950 Bryant.... 1.81/57 tion extending lengthwise within the housing through 2,841,236 7/1958. Moerke... 181/40 the partition and having an inlet in'the outlet chamber 2,960,179 y 131/53 UX and including an outlet portion extending at least par- 3,383,769 6/1968 I 81/60 X tially in the inlet chamber and outwardly through said 3,419,107 l2/l968 JOZCPaIUS 181/40 side wall 7 I FOREIGN PATENTS OR APPLICATIONS 54,137 9/1969 Germany, 181 53 12 Chums D' s 1 (0? Q5 v Q? /7 g a I y I m Y @5- 2/ I 2/ p a6 1 l 1| I Q v I. 1

o o o o o o 6-6 Q oooeoo 0 50 I I /oo o'oo o o.od) q $3 63 i O a o o o 0 M6 27 -5/ 47 I o /o o 0 0 0 0 o 3 7 49 1 7/ 655 as 1 r I 25 -27 25 67 I I 1 EXHAUST'MUFFLER BACKGROUND or THE INVENTION SUMMARY OF THE INVENTION The invention provides .a muffler which beneficially reduces noise level while having a substantially minor effect on engine power. In accordance with the inven-' tion, the muffler is sub-divided into various chambers by dished or partially spherical end walls and intermediate partitions. In addition, the partitions are provided with ports which provide communication between the chambers, which are preferably formed, at least in part,

from the material of the partitions, which preferably include beveled inlet margins which merge with the dished or partially spherical partitions, and which preferably have a relatively short length axially of the muffler.

- In further accordance with the invention, one or more discharge tubes are provided, which discharge tubes preferably extend lengthwise within the housing for a substantial distance and have a relatively small cross-sectional area as compared to length within the housing. As a consequence, the considerable length of the discharge tubes apparently prevents significant backflow of atmospheric air into the mufflers and thereby serves to prevent backfiring'within the muffler.

In still further accordance with the invention, there is provided a muffler including ports which afford communication between chambers and which are of rela tively short length, together with one or more tail pipes which have-a substantial length within the muffler and which have a relatively small cross sectional area in relation to length within the mufiler.

Still further, the invention provides a deflector plate which is preferably perforated and which is mounted in an inlet chamber in the path'of incoming exhaust gases so as to diffuse such incoming exhaust gases throughout the inlet chamber and to thereby reduce structural de-. formation caused by heat concentration.

One of the principal objects of the invention is the provision of a muffler which has superior noise reducing capability, together with little apparent disadvanta-.

Before explaining the invention in detail, it is to be understood that the invention is not limited-in its application to the details of construction and arrangement of parts set forth in the following general description or illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood-that the phraseology or terminology em ployed herein is for the purpose of description and not of limitation.

GENERAL DESCRIPTION Shown in the drawings is a muffler 11 which embodies various of the features of the invention and .which includes a housing or shell 13 defined by an arcuately extending outer or side wall 15. Preferably, the outer or side wall 15 is cylindrical in form. -At its ends, the side wall 15 is closed by respective end walls 17 and 19 which are dished. Although other arcuate shapes and arrangements could be used, the illustrated end walls 17 and 19 are each partially spherically shaped and are preferably concavely inwardly arranged, Connected to the outer surface of the end walls 17 and 19 are respective support brackets 21.

Further in accordance with the invention, the housing 13 is sub-divided into an inlet chamber 23 and an outlet chamber 25 by a first dished partition 27 which is located so that the inlet chamber 23 has a length slightly greater than about A the length of the housing 13. Although other arcuate shapes could be employed, in the illustrated construction, the partition 27 is partially spherically shaped and extends convexly with respect to the inlet chamber 23, although the partition 27 could extend convexly with respect to the outlet chamber 25.

Still further inaccordance with the invention, the

outlet chamber 25 is further sub-divided into an intermediate sub-ehamber 29 and an outlet sub-chamber'3l by a second, dished partition 33 located generally centr'ally of the length of the outlet chamber 25. While other arcuate shapes could be employed, the illustrated partition '33 is partially spherically shaped and extends concavely with respect to the intermediate sub chamber 29, although the partition 33 could extend concavely with respect to the outlet sub-chamber 31.

Still further in accordance with the invention, the first partition 27 is provided with at least one port 35 which is preferably formed, at least in part, from the material of the first partition 27 and which includes a tubular part or portion 37 extending for a relatively short length from the inlet chamber 23 and into the outlet chamber 25 and including an inlet 39 having a margin which merges with the first partition 27 and has a curved cross section in a plane extending radially with respect to the length or axis of the tubular portion. The port 35 also includes an outlet 41 at the end of the tubular portion 37 spaced from the first partition 27 and located inwardly of the outlet chamber 25 in a plane generally perpendicular. to the length of the tubular respect to the discharge tube 59.

larly spaced relation to the first port 35 and of generally the same construction.

Further in accordance with the invention, the second partition 33 includes at least one port 45 communicating between the intermediate sub-chamber 29 and the outlet sub-chamber 31. In the preferred embodiment of the invention, a second port 47 is also employed, which ports 45 and 47 are located in angularly spaced relation to each other and to the ports 35 and 43 in the first partition 27.

Each of the ports 45 and 47 in the second partition 33 is preferably formed, at least in part, from the material of the second partition 33 and includes a tubular portion 49 having an inlet 51 with a margin which merges with the second partition 33 and has a curved cross section in a plane extending radially with respect to the length or axis of the tubular portion. The ports 47 and 45 also include an outlet 53 at the ends of the tubular portions 49 located inwardly of the outlet subchamber 31 and in a plane generally perpendicular to the length of the tubular portions 49. Although the tubular portions could extend at an angle to the length of the muffler housing 13, it is preferred to form the ports 45 and 47 as illustrated with the tubular portions 49 extending parallel to the length of the muffler housing 13.

In still further accordance with the invention, the muffler 11 includes an inlet tube or duct 55 which extends radially outwardly from the inlet chamber 23 through the side wall and includes, at its outer end,

. an attachment flange 57.

In still further accordance with the invention, the muffler further includes at least one outlet or discharge tube or duct or tail pipe 59 which communicates with the outlet sub-chamber .31 and extends outwardly through the side wall 15. In the preferred embodiment, a second discharge tube 61 extends in generally parallel relation to the discharge tube 59. I I

While the discharge tube or tubes could pass directly through that portion of the side wall 15 which defines I the outlet sub-chamber 31, it is preferred to at least partially locate the .outlet tubes 59 and 61 lengthwise within the housing 13 in inward and outward radial relation to each other. More specifically, it is preferred that the discharge tubes 59 and 61 extend within the housing for a substantial length and have a relatively small cross sectional area as compared to the length thereof. In this regard, it is preferred to construct the tubes 59 and 61 with a ratio between the cross sectional area (in square inches) and the length within the housing 13 (in inches) within the range of 0.25 to0.073, which ratio is expressed as a decimal by dividing the length into the area. Still more specifically, in the illustrated construction, the discharge tubes 59 and 61 are located in co-planar relation to each other in a plane slightly offset from, and parallel to, a plane extending diametrically of the tubularhousing 13 and with the discharge tube 61 being located radially inwardly with Still further, each of the outlet tubes 59 and 61 is formed with an elongated inlet portion 63 which extends lengthwise of the Imuffler housing'13 through both the first and second partitions 27 and 33, respectively, and which includes an inlet 65 in the outlet sub- .chamber 31. Each ofthe'outlet tubes 59 and 61 also includes an outlet portion 67 which communicates with the inlet portion 63 and which extends, at least in part, through the inlet chamber 23 and outwardly through the side 'wall '15 defining the inlet chamber 23. As

shown in FIG. 3, both the outlet or discharge tubes 59 and 61 have an identical length except that the radially outward tube 59 has a larger outlet portion 67 so that theoutlet portions 67 of both of the discharge tubes 59 and 61 terminate at about the same place. As a consequence, the inlet portion 63 of the radially inner discharge tube 61 extends within the outletsub-chamber 31 for a greater distance than does the inlet portion 63 I of the radially outer discharge. tube 59.

In order to facilitate assembly, the first and second partitions 27 and 33 respectively can be provided with' radially spaced and relatively short ports or tubes 69 which receive the discharge tubes 59 and 61 and which connected to and supported by the radially inner dis charge tube 61, and which includes a series of perfora tions 73. Accordingly, the deflector plate 71 is arranged so as to disperse or deflect the incoming exhaust gases throughout the inlet chamber 23 so as thereby to prevent structural deformation caused by heat concentration in a particular area. A

The disclosed muffler 11 beneficially reduces noise level withoutsubstantially reducing the engine power and, in addition, substantially reduces or eliminates muffler backfiring. More specifically, the curved, dished, or partially spherical condition of the end walls 17 and 19 and the partitions 27 and 33 is believed to prevent or reduce drumming orshell noise'produced by the muffler in response to excitation by the exhaust gases within the various chambers. The length of the discharge tubesor tail pipes 59 and 61 from the outlet portion 67 to the outlet sub-chamber 31 is also believed to beneficially substantially reduce or eliminate backfiring within the muffler by preventing significant backflow of atmospheric air into the muffler for combinapressure loss prior to the discharge tubes 59 and 61 so as to permit maximum allowable back pressure loss to occur in the discharge tubes 59 and 61. The shortness of the tubular portions 37 and 49 is also believed to reduce the resonant frequency of the muffler. In addition to reducing backfiring, the discharge tubes 59 and 61 also beneficially function to reduce the amplitude of low frequency noise.

Various of the features of the invention are set forth in the following claims. I

We claim:

1. A muffler comprising an elongated housing having an elongated outer wall and including a partition dividing said housing into an inlet chamber and an outlet chamber, said partition including a port communicating between said inlet chamber and said outlet chamher, an inlet tube extending through said elongated outer wall and communicating with said inlet chamber, and a discharge tube including an inlet portion extending lengthwise of said housing through said partition and having an inlet in said outlet chamber, said inlet portion being imperforate in said inlet chamber, and an imperforate outlet portion communicating with said inlet portion and extending at least partially in said inlet chamber and outwardly through said elongated outer wall. 1

2. A muffler in accordance with claim 1 wherein said discharge tube has a relatively long length in said housing and a relatively small cross sectional area as compared with said length, the ratio of 'said cross section area to said length in said housing of said discharge tube being between 0.25 and 0.073 with said length in inches divided into said area in square inches.

3. An exhaust muffler in accordance with claim 1 including a perforated deflector mounted in said inlet chamber inthe path of exhaust gas entering said inlet chamber from said inlet tube. I

4. An exhaust muffler in accordance with claim 3 wherein said deflector is supported on said discharge tube. i

5. An exhaust muffler in accordance with claim 1 and further including a second discharge tube extending in, generally parallel relation to said first mentioned discharge tube.

6. A muffler in accordance with claim 1 including a second port located in said partition and angularly spaced from said first mentioned port, said first mentioned port and said second port each extending from said inlet chamber into said outlet chamber and each including a tubular part with-an inlet having a margin which merges with said partition and has an arcuate form in a plane extending radially of the length of said tubular part.

7. A muffler-in accordance with claim 6 wherein said tubular parts of said ports are formed, at least in part,

from the material of said partition and have a length extending parallel to the length of said housing, and an outlet located in a plane perpendicular to the length of mentioned partition and dividing said outlet chamber into an intermediate sub-chamber located adjacent to said first partition, and an outlet sub-chamber. said second partition including therein a port communicating between said intermediate and outlet sub-chambers, an inlet tube extending through said outer wall and com- .municating with said inlet chamber, and a discharge tube including an inlet portion communication with said outlet sub-chamber and extending lengthwise of said housing through said first and second partitions; said inlet portion being imperforate in said inlet chamber and in said intermediate sub-chamber, said discharge tubealso including an imperforate outlet portion communicating with said inlet portion and extending at least partially in said inlet chamber and out wardly through said elongated outer wall.

- 9. An exhaust muffler in accordance with claim 8 and further including a second discharge tube extending in parallel relation to said first mentioned discharge tube.

10. An exhaust muffler in accordance with claim 9 including a perforated deflector mounted in said inlet chamber in the path of exhaust gas entering said inlet chamber from said inlet tube.

11. An exhaust muffler in accordance with claim 10 wherein said deflector is supported on one of said discharge tubes.

12. A mufiler in accordance with claim 11 wherein said ports are formed, at least in part, from the material of the associated one of said partitions and have a length extending parallel to the length of said housing,

length of said tubular parts. 

1. A muffler comprising an elongated housing having an elongated outer wall and including a partition dividing said housing into an inlet chamber and an outlet chamber, said partition including a port communicating between said inlet chamber and said outlet chamber, an inlet tube extending through said elongated outer wall and communicating with said inlet chamber, and a discharge tube including an inlet portion extending lengthwise of said housing through said partition and having an inlet in said outlet chamber, said inlet portion being imperforate in said inlet chamber, and an imperforate outlet portion communicating with said inlet portion and extending at least partially in said inlet chamber and outwardly through said elongAted outer wall.
 2. A muffler in accordance with claim 1 wherein said discharge tube has a relatively long length in said housing and a relatively small cross sectional area as compared with said length, the ratio of said cross section area to said length in said housing of said discharge tube being between 0.25 and 0.073 with said length in inches divided into said area in square inches.
 3. An exhaust muffler in accordance with claim 1 including a perforated deflector mounted in said inlet chamber in the path of exhaust gas entering said inlet chamber from said inlet tube.
 4. An exhaust muffler in accordance with claim 3 wherein said deflector is supported on said discharge tube.
 5. An exhaust muffler in accordance with claim 1 and further including a second discharge tube extending in generally parallel relation to said first mentioned discharge tube.
 6. A muffler in accordance with claim 1 including a second port located in said partition and angularly spaced from said first mentioned port, said first mentioned port and said second port each extending from said inlet chamber into said outlet chamber and each including a tubular part with an inlet having a margin which merges with said partition and has an arcuate form in a plane extending radially of the length of said tubular part.
 7. A muffler in accordance with claim 6 wherein said tubular parts of said ports are formed, at least in part, from the material of said partition and have a length extending parallel to the length of said housing, and an outlet located in a plane perpendicular to the length of said tubular parts.
 8. A muffler comprising an elongated housing having an elongated outer wall and including a first partition dividing said housing into an inlet chamber and an outlet chamber, said first partition including therein a port communicating between said inlet and outlet chambers, a second partition spaced from said first-mentioned partition and dividing said outlet chamber into an intermediate sub-chamber located adjacent to said first partition, and an outlet sub-chamber, said second partition including therein a port communicating between said intermediate and outlet sub-chambers, an inlet tube extending through said outer wall and communicating with said inlet chamber, and a discharge tube including an inlet portion communication with said outlet sub-chamber and extending lengthwise of said housing through said first and second partitions, said inlet portion being imperforate in said inlet chamber and in said intermediate sub-chamber, said discharge tube also including an imperforate outlet portion communicating with said inlet portion and extending at least partially in said inlet chamber and outwardly through said elongated outer wall.
 9. An exhaust muffler in accordance with claim 8 and further including a second discharge tube extending in parallel relation to said first mentioned discharge tube.
 10. An exhaust muffler in accordance with claim 9 including a perforated deflector mounted in said inlet chamber in the path of exhaust gas entering said inlet chamber from said inlet tube.
 11. An exhaust muffler in accordance with claim 10 wherein said deflector is supported on one of said discharge tubes.
 12. A muffler in accordance with claim 11 wherein said ports are formed, at least in part, from the material of the associated one of said partitions and have a length extending parallel to the length of said housing, and an outlet located in a plane perpendicular to the length of said tubular parts. 